Predation effects on mean time to extinction under demographic stochasticity

Background/Question/Methods

Methods for predicting the probability and timing of a species’ extinction are based on a combination of theoretical models and empirical data, and focus on single species population dynamics. Of course, species also interact with each other, usually forming complex networks of interactions. However, models to assess extinction risk often lack explicit incorporation of interspecific interactions.

We derive a birth and death process in which the death rate includes a general nonlinear expression for the functional response of predation. We then investigate the effects of the foraging parameters (e.g. attack rate and handling time) on the predicted time to extinction.

Results/Conclusions

Mean time to extinction varies by orders of magnitude when we alter the foraging parameters, even when we exclude the effects of these parameters from the equilibrium population size.

In particular we observe an exponential dependence of the mean time to extinction on handling time.

These findings clearly show that accounting for the nature of interspecific interactions is likely to be critically important when estimating extinction risk. We intend to extend this work to investigate the interactions between species’ interaction parameters and extinction risk in complex communities.